Methods for dissociating tris(aryl)boraneether complexes are well known. These methods include evaporation of the ether with sublimation; reactive exchange, in which a compound that has a higher affinity for the ether is added; and azeotropic distillation from a higher-boiling hydrocarbon solvent. Some of these methods are described in U.S. Pat. Nos. 5,510,536, 5,600,004, 5,693,261, and EP 838466A2. However, the tris(aryl)boraneether complexes formed when tetrahydrofuran is the ether are especially strong and difficult to separate. A satisfactory yield of the separated tris(aryl)borane is often not obtained by azeotropic distillation when tetahydrofuran is the complexed ether. Thus, there remains a need for a method which more completely separates tris(aryl)boranes from tetrahydrofuran.